By Orthopaedics International and Sports Medicine International

August 2011 Issue

Ortho Insider

DR. CHAN BENG KUEN Specialist Orthopaedic Surgeon

MBBS (S'pore), M.MED

(Surgery), FRCS (Edin), FRCS

(Glas), FAMS (Orth)

Sports Surgery, Shoulder &

Upper Limb Surgery

DR. FRANCIS WONG Specialist Orthopaedic Surgeon

MBBS (S'pore), FRCS (Edin),

FRCS (Glas), FAMS (Orth)

Adult Reconstruction,

Joint Replacement, Paediatric

Orthopaedics and Trauma

DR. LESLIE LEONG Specialist Orthopaedic Surgeon

MBBS (S'pore),

M.MED (Surgery), FRCS (Edin)

Adult Reconstruction and

Joint Replacement

DR. LIANG TE SHAN Specialist Orthopaedic Surgeon

MBBS (S'pore), FRCS (Edin),

FRCS (Glas), FAMS (Orth)

Adult Reconstruction, Joint Re-

placement & Musculoskeletal

Tumour Surgery

DR. PATRICK GOH

Specialist Sports Physician

MBBS (S’pore),

MSS (Sports-Med USA)

Sports and Exercise Medicine

DR. THO KAM SAN Specialist Orthopaedic Surgeon

MBBS (S'pore),

M.MED (Surgery), FRCS (Edin),

FAMS (Orth)

Sports Surgery, Arthroscopic

Reconstruction, knee and

shoulder surgery

DR. WONG YUE SHUEN Specialist Orthopaedic Surgeon

MBBS (S’pore), FRCS (Edin),

MSc (Biomedical Eng)

Sports Surgery, Foot and Ankle,

Knee Surgery,

Trauma Orthopaedics

Current Trends in

Total Knee Replacement

By Dr Leslie Leong

Specialist Orthopaedic Surgeon

Total Knee Replacement (TKR) has been

around for a few decades. It has improved

the lives of many patients crippled with dis-

abling arthritis. However, with any evolving

technology, it is not without its drawbacks.

Traditionally, it has been taught that joint

replacement should be performed as a last

resort, in patients over 60 years of age and

are sedentary in nature. This was often due

to the polyethylene(PE) insert having a user

life of 10-15 years, and (in)accuracy of com-

ponents inserted.

This picture shows a severely worn out PE

insert which allowed the femoral component

to articulate onto the tibial baseplate, break-

ing it eventually.

TKR done 1993, but put into varus, resulting

in accelerated PE insert wear.

Previously, PE inserts were sterilised in

air, packed into sterile boxes containing air

and often these were left on the shelf for

years before usage, resulting in oxidation,

rendering them brittle. Currently, all PE

inserts are sterilised and stored in an oxy-

gen free environment. This has helped ex-

tend their shelf and in vivo life.

Three recent innovations have helped to

improve TKR longevity. Radiation and

heat causes cross-linking of PE molecules

and helps remove free radicals. This makes

it more wear resistant, albeit slightly more

brittle, and has been widely used in hip

replacement for nearly a decade. However,

it has only been used in the knees recently,

as the wear environment in the knee is

more complex and stressful than the hip.

Several companies now carry this product.

(Eg, Prolong, X3)

The second innovation is PE doped with

vitamin E. Vitamin E, a well known anti-

oxidant, binds any remnant free radicals

and reduces oxidation and hence decrease

PE wear. Currently, only one company has

combined both vitamin E and cross-linking

(E-Poly).

The third innovation has been to improve

the hardness and smoothness of the femo-

ral component to reduce PE wear. One

such product, Oxinium, is made from zir-

conium. Using high heat, temperature and

oxygen, the surface transforms into a ce-

ramic-like surface with increased hardness

and smoothness. Combined with cross-

linked PE, in vitro wear has been greatly

reduced, even when tested against a rough-

ened femoral component. For patients aged

45-60, this is a game-changer, and their

prosthesis may now last a lifetime. FDA

has approved this TKR combination

(Verilast) to be marketed with a 30 year

lifespan, the 1st in industry.

Permit No . MICA (P)176/10/2010

Welcome to this issue of Ortho Insider, Osteoarthritis is the single most common form of arthritis in Singapore. It is a leading cause of disability and reduction in daily function, and is set to become even more problematic as our population ages. Joint replacement surgery is a viable treatment option in the advanced stages of OA. Our featured article focuses on recent trends and innovations in this area.

Happy reading!

Ortho Insider, August 2011 Issue

Our Locations :

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Medical Centre

1 Orchard Boulevard

Singapore 248649

Tel : 6836 9688

Fax : 6836 6869

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Medical Centre Blk B

820 Thomson Road

Singapore 574623

Tel : 6352 7678

Fax : 6352 7680

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#02-42 Gleneagles

Hospital Annexe Block

6A Napier Road

Singapore 258500

Tel: 6476 7266

Fax: 6476 2066

Mt. Elizabeth #05-08 Mt Elizabeth

Medical Centre

3 Mt Elizabeth

Singapore 228510

Tel. 6737 6386

Fax : 6737 6836

Orthopaedics International, Neurosurgery International and Sports Medicine International are a group of registered specialist practices

comprising 8 orthopaedic surgeons, a neurosurgeon and a sports physician. Operating out of 4 locations within Singapore, we aim to provide patients

with comprehensive and professional care for all musculoskeletal, neurosurgical and sports-related conditions. Each specialist brings a range of Interests,

expertise and sub-specializations to the group, and is also a senior doctor with a minimum of 20 to 30 years of relevant clinical experience behind him.

We strongly believe in a team approach, so that every patient of ours will be treated with the highest standards of expertise and care that are available.

www.ortho-intl.com

www.sportsmed-intl.com

www.neuro-intl.com

Registered Practices :

Mobile bearing knee pros-

theses (where the insert

pivots on the tibia base-

plate) have been around for

2 decades and were touted

to improve mobility and

reduce PE wear. However,

most studies have not found

any difference in long term

survivorship compared to

standard fixed bearing

knees. Hence the extra cost

may not be justified.

Having the best materials is

of little benefit if they are

implanted poorly. To im-

prove implant position,

computer assisted naviga-

tion was invented to pro-

vide instant feedback on the

bone cuts, implant position

and limb alignment. Navi-

gation itself is not without

its problems, chief of which

is “garbage in, garbage

out” when acquiring the

reference points and a

small risk of fractures from

the pins used to mount the

navigation trackers. An experienced surgeon however can achieve

equally good results if he routinely double checks his cuts and soft

tissue balancing.

To overcome these issues, shorten operating time and assist in mini-

mally invasive surgery (now done routinely), patient specific/

matched instrumentation was recently invented.

Dr. Leslie Leong was awarded the Ministry of Health Manpower Development Programme (HMDP) Scholarship to train at Toronto

Western Hospital in Adult Reconstruction in Hip and Knee Arthroplasty. He established the Adult Reconstruction Service in Changi

General Hospital and pioneered the use of minimally invasive surgery in hip and knee arthroplasty, computer assisted surgery, alter-

native bearings in hip and knee replacement, various forms of partial knee replacement, revision arthroplasty and multi modal pain

management.

Essentially, the lower limb and knee is imaged and the results

sent overseas. These are digitised and a custom made jig is

fashioned to fit exactly over the knee. This is shipped back to

the surgeon, who will use it to make the bone cuts more pre-

cisely, consistently. This technology is likely to benefit

younger patients much more than elderly, as PE wear will

manifest itself only after 10-15 years.

Options to TKR include unicondylar or bicompartment knee

replacement. It is possible now to replace a specific compart-

ment of the knee, rather than the entire knee. This procedure

can be viewed as a “pre-TKR surgery”. With cruciate preser-

vation and less surgery, recovery is faster. However, patients

qualifying for these implants are not common, as they need to

be treated earlier rather than wait for all compartments to be

involved.

Left; unicondylar knee replacement. Centre; bicompartment

knee replacement. Right; TKR

In summary, TKR has undergone a sea-change over the past 5

years. Hip and Knee surgeons now have a wider armamentar-

ium to tackle knee arthritis and provide a longer lasting

implant.

For enquiries, pls email to lcsleong@gmail.com

Oxinium Femoral Component

Minimally Invasive TKR with navi-

gation. Note the trackers pinned into

the femur and tibia shaft